Electromagnetic acoustic transducer (EMAT) technology has been applied to molten metals to achieve non-contact heating and/or mixing of the melt. As described for example in U.S. Pat. No. 7,534,980, a molten metal may be contained in a mold or crucible and exposed to time-varying and static magnetic fields to induce a large oscillatory electromagnetic force, or pressure, on the sample. The induced acoustic driving force is bi-directional, alternately compressing and stretching the sample, promoting mixing, cavitation and heating of the melt. However, at high static magnetic fields, the amplitude of the oscillations may be so high that excessive heating and stressing of the sample occurs, leading to contamination of the melt with the mold material and/or fracturing of the mold during EMAT processing. Alternately, mold-melt interactions can be a direct result of basic thermodynamics leading to reaction and potential undesirable dissolution of elemental constituents from the mold and subsequent solution or precipitation of those in the melt, causing unexpected or unwanted chemistry changes. Another mechanism is the forceful erosion of the mold material aided by the EMAT excitation-produced melt cavitation process and subsequent bubble collapsing, which may ablate mold material into the melt. It would be advantageous to develop a method of molten material processing that allowed heating and non-contact mixing to occur without risk of contamination from a mold, or other problems.